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Abstract

Introduction: In pediatric critical care, accurate placement of endotracheal tubes prevent unplanned extubation or unrecognized bronchial intubation. The optimal position of the endotracheal tube is believed to be 2.0 cm above the carina so that movement of the head does not raise the ETT out of the airway nor push it in to an endobronchial position. The gold standard for confirmation has been the chest radiograph. To reduce exposure to radiation, and ensure optimal position immediately after extubation, non-radiographic techniques to determine optimal placement have included formulas based on body size, ETT size, gestational age, and measured markings on the end of the endotracheal tube. Formulas that relate the length of the trachea to variables such as age, weight, or height are inconsistent, and may be less accurate for children with obesity, failure to thrive, or scoliosis which affect height. Ulnar length is preserved in these populations, and is unaffected by body habitus or neuromuscular disease. Hypothesis: Ulnar length can be used to determine the optimal depth of oro-tracheal intubation. Methods: Any orotracheally intubated child admitted to the pediatric or cardiothoracic intensive care unit was eligible. Routinely obtained chest radiographs were used to determine endotracheal tube position and distance from the carina. The patient’s ulnar length, height, and depth of endotracheal tube insertion were obtained. Optimal endotracheal tube position, calculated as 2 cm above the carina was measured based on current tube position. Ideal ETT depth was plotted against the patient’s ulnar length, and linear regression was used to determine a predictive equation. Results: 58 patients were included. Optimal depth of the endotracheal tube plotted against ulnar length resulted in a linear relationship, given by the following formula: depth of ETT insertion in cm = 0.72(ulnar length in cm) + 5.2 (R2 = 0.84). Conclusions: Optimal depth of endotracheal tube insertion can be rapidly estimated using ulnar length. This information can be used to ensure correct endotracheal tube placement, potentially reducing the need for chest radiographs.